The invention relates generally to implantable medical devices and in particular to implantable medical devices for coaptation of a body lumen.
Various implantable devices, such as inflatable/distensible medical devices, are known in which the distensible medical devices are implanted into the tissue of a human to treat urinary incontinence. These devices have typically relied upon restricting or constricting the urethra of the patient to maintain continence.
U.S. Pat. No. 4,773,393 to Haber et al. is an attempt at such a proposed device. U.S. Pat. No. 4,773,393 relates to a hypodermically implantable genitourinary prosthesis which provides an extensible, inflatable tissue expanding membrane to be located in proximal urethral tissue to add bulk to these tissues for overcoming urinary incontinence by localized increase in tissue volume.
U.S. Pat. No. 4,802,479 to Haber et al. is an attempt at an instrument for dispensing and delivering material to an inflatable membrane of a genitourinary prosthesis within the tissues of a patient for overcoming urinary incontinence. U.S. Pat. No. 4,832,680 to Haber et al. relates to an apparatus for hypodermically implanting a genitourinary prosthesis comprising an extensible containment membrane for retaining a fluid or particulate matter which is injected from an external source.
U.S. Pat. No. 5,304,123 to Atala et al. relates to a detachable membrane catheter incorporated into an endoscopic instrument for implantation into the suburethral region of a patient. Also, U.S. Pat. No. 5,411,475 to Atala et al. discusses a directly visualized method for deploying a detachable membrane at a target site in vivo. U.S. Pat. No. 5,830,228 to Knapp et al. relates to a method and system for deployment of a detachable balloon at a target site in vivo.
Once inflated, these devices maintain pressure on the urethra of the patient in an attempt to assist with continence. However, these devices are prone to being under or over inflated at time of implant, leading to undesirable postoperative results. For example, if the devices are overinflated it may cause the urethra to be restricted too tightly, and the patient is at risk for retention, a condition where the patient cannot pass urine. Such a condition could lead to kidney damage, necessitating major corrective surgery or at minimum use of self-catheterization to empty the bladder on a regular basis thus increasing the risk of urinary tract infection.
Furthermore, once these devices have been implanted within the patient, the only means of removing them in the event of a postoperative problem or device malfunction is through major surgery. Also, the devices are not secured within the tissues of the patient, so there is the possibility of the devices migrating back along the pathway created in inserting them, a problem which has been noted with prior art devices. Thus, an important medical need exists for an improved implantable device for treating urinary incontinence.
The present invention provides an implantable device and a method for its use in restricting a body lumen. In one embodiment, the body lumen is a urethra, where the implantable device is used to coapt the urethra to assist the patient in urinary continence. The implantable medical device has the advantage of being adjustable both at the time of implantation and postoperatively. This postoperative adjustability of the implantable medical device allows a physician to regulate the amount of pressure applied to the urethra to ensure continence of the patient and to minimize iatrogenic effects.
In one embodiment, the present subject matter includes an implantable device assembly for controllable coaptation of a body lumen. The implantable device assembly includes an implantable device which includes an adjustable element and a tubular elongate body. The adjustable element includes a continuous wall, including an inner surface defining a chamber. The tubular elongate body includes a peripheral surface, a proximal end and a distal end, where the peripheral surface is connected to and sealed to the adjustable element. The tubular elongate body further includes at least a first interior passageway which extends longitudinally in the tubular elongate body from a first opening at the proximal end to a second opening in fluid communication with the chamber of the implantable device. This allows for adjustably expanding or contracting the adjustable element by applied flowable material introduced through the first opening. The implantable device assembly also includes a sheath, where the sheath includes a wall having an inner surface which defines a channel through which at least a portion of the implantable device can pass.
In one embodiment, the implanted device is inserted into body tissue by passing the device through the sheath. The sheath is first inserted into the tissue of the patient and then the implanted device is moved through the channel of the sheath. In one embodiment, the implanted device is moved through the sheath through the use of a push rod, where the push rod is inserted into the first interior passageway. As the push rod is inserted into the first interior passage way it comes into contact with a closed end distal to both the first opening and second opening of the first interior passage way. Force can then be applied to the push rod to move the implanted device at least partially through the channel of the sheath.
In an alternative embodiment, the tubular elongate body includes a second interior passageway which extends longitudinally along at least a portion of the tubular elongate body from an inlet to a closed end. The second interior passageway is of sufficient diameter to receive the push rod which contacts the closed end to allow force applied to the push rod to move the implanted device at least partially through the channel of the sheath.
In an additional embodiment, the implantable device assembly can further include a sleeve having a longitudinal slot, where at least a portion of the implanted device is housed in the volume defined by the sleeve. In one embodiment, the sleeve and implanted device are passed through the sheath so as to extend the adjustable element past the distal end of the sheath. The adjustable element is then expanded so that contact is made with the tissue. In one embodiment, the sheath is withdrawn from the body, after which the sleeve is then either passed around a portion of the implanted device or a portion of the implanted device deforms to allow the implanted device to pass through the sleeve. In an alternative embodiment, the sleeve is withdrawn from the body, after which the sheath is passed around a portion of the implanted device.
In an additional embodiment, the implantable device includes a rear port element coupled to the proximal end of the tubular elongate body. In one embodiment, the rear port element is releasably attached to the tubular elongate body. The rear port element including a cavity in fluid communication with the first opening of the first interior passageway. This allows for fluid volume passed through the rear port element to either expand or contract the size of the adjustable element. In one embodiment, the rear port element has an elastic septum to receive a needle through which flowable material can pass to expand or contract the adjustable element.
The sheath of the present subject matter also includes a first portion and at least one of a second portion, where the second portion is of a lesser strength compared to the first portion. In one embodiment, the second portion extends longitudinally along the wall to allow for the wall of the sheath to be separated. In one embodiment, the second portion of the wall includes scorings extending longitudinally along the wall which create a weak area over which the sheath can be torn. In an additional embodiment, the wall of the sheath can include two scorings extending longitudinally along the wall to allow for the sheath to be separated into two pieces. Alternatively, the sheath can include a slit through the wall, where the slit extends longitudinally along the wall.
In an additional embodiment, the implanted device further includes a tip suitable to penetrate tissue. In one embodiment, the tip is positioned, or is formed, at the distal end of the tubular elongate body. Alternatively, the distal end of the push rod forms the tip, where the tip is exposed at the distal end of the tubular elongate body when the distal end of the push rod passes through an outlet end in the second interior passage way.
Finally, an important feature of the implantable device of the present invention relates to the adjustable element or membrane which is accessible for subsequent adjustment in volume through the rear port element located under a patient""s skin, remotely from the adjustable element. Another important feature of the present invention over the prior art devices is the convenient in vivo postoperative adjustability of both pressure and size of the adjustable element.